Abstract

As explained in Chapter 4, most realistic Arc Routing Problems are known to be NP-hard. Therefore we can expect that there will be certain instances which are impossible to solve to optimality within a reasonable time. However, this does not mean that all instances will be impossible to solve. It may well be that an instance which arises in practice has some structure which makes it amenable to solution by an optimization algorithm. Since, in addition, significant costs are often involved in realworld instances, research into devising optimization algorithms is still regarded as important.